SAN FRANCISCO (AP) -- Carlos Gonzalez and the Colorado Rockies are confident it's too early to be concerned about Jorge De La Rosa.
The left-hander gave up a grand slam to opposing pitcher Madison Bumgarner, who drove in a career-high five runs for the San Francisco Giants in their 6-5 victory Friday night.
De La Rosa (0-2) allowed six runs and four hits in 4 1-3 innings, leaving him with a 9.69 ERA. He struck out six and walked two.
"It's only three games," Gonzalez said. "I know he's not pitching like he was last year, but that happens. Everybody goes through tough times. I'm not worried about him. He has a lot of opportunities to get better."
De La Rosa, the team's opening day starter, failed to get out of the fifth inning for the third straight start. He had a 3-0 lead in the third before allowing a triple to Brandon Crawford and a sacrifice fly to Bumgarner.
In the fourth, De La Rosa gave up a single and a walk but then got two outs. He hit Brandon Hicks with a pitch to load the bases and walked Crawford to force in a run.
"His command got away from him," Rockies manager Walt Weiss said. "He got some balls up and out over the plate. He's got a good track record and I put a lot of stock into that. It looked like he was locked in, and then in a matter of an inning it gets away from him."
Bumgarner hit the next pitch into the left field bleachers, the second grand slam by a Giants pitcher since the team relocated from New York to San Francisco in 1958. Shawn Estes did it against the Montreal Expos on May 24, 2000.
"With Bumgarner, you have to treat him like another hitter," Gonzalez said. "Over the years he's proven he can handle the bat. He saw a cookie and took advantage. The tough one is the hit by pitch."
Gonzalez gave the Rockies their early lead, hitting a two-run homer that landed in McCovey Cove for the second splash hit of his career.
"Any time you face Bumgarner you know it's going to be a tough at-bat," Gonzalez said. "You have to battle every pitch. He threw me a 3-2 curveball and there's no way I'm sitting on it. I just reacted. It was nice to take a 3-0 lead, but things changed after that."
Troy Tulowitzki's sore quadriceps kept him out of Colorado's starting lineup. He pinch-hit in the ninth and struck out looking against closer Sergio Romo to end the game.
The Rockies also were without catcher Wilin Rosario, who hurt his left wrist while sliding during Wednesday's 8-1 win against the Chicago White Sox.
Colorado cut it to 6-5 on Charlie Blackmon's pinch-hit single off reliever Santiago Casilla in the eighth but made two baserunning blunders.
Blackmon strayed too far off second and was thrown out after Casilla made a nice play to spear Jordan Pacheco's fielder's choice. Pacheco then got doubled up when center fielder Juan Perez caught DJ LeMahieu's fly ball and threw to first.
"I saw the ball in the air and I thought it would get by him," Blackmon said. "If it does, we have a chance to win."
The Rockies went up 1-0 in the first when leadoff hitter Brandon Barnes singled and later scored from third while Josh Rutledge was caught trying to steal second.
Rutledge started in place of Tulowitzki and went 3 for 4.
NOTES: Gonzalez has five career home runs off Bumgarner, the most given up by the San Francisco lefty. ... LHP Brett Anderson (0-2) pitches Saturday against San Francisco RHP Matt Cain (0-1).